Solving Ertha Diggs’s Ancient Stone Arch Mystery

According to legend, when the Romans made an arch, they would make the architect stand under it while the wooden support was removed. That was one way to be sure that architects carefully designed arches that wouldn’t fall! Educator Michael Serra led AAAS symposium participants in a surprising and fun hands-on arch construction project using familiar objects—Chinese take-out cartons—in an unfamiliar way: “these are stone voussoirs from an ancient miniature bridge uncovered by my friend, archaeologist Ertha Diggs. She has asked us to determine the number of stones in the original bridge.” This makes it possible to understand both arch mechanics and the mathematics behind the arch through actually constructing them.